The present proposal involves a series of studies that utilize attentional training techniques with mentally retarded children and nonretarded children. While most research efforts involving mentally retarded populations have emphasized mediational deficits in information processing, the present series of studies explores the role of perceptual salience in inducing rapid detection of relevant stimulus relationships. The general hypothesis is that the discrimination learning ability of high-functioning mentally retarded groups and nonretarded groups can be facilitated equally well through appropriate perceptually based manipulations. In certain studies, the relative contributions of perceptual salience and exposure to rule-based learning will be explored. The specific aims are to: (a) determine the degree of perceptual salience necessary for the inducement of oddity learning in mentally retarded and nonretarded children; (b) determine the importance of rule utilization in oddity learning for both mentally retarded and nonretarded children; (c) determine the generalizability of the oddity learning induced; (d) determine the facilitative effects of a perceptual intervention on component learning; and (e) evaluate the potential effects of the subject's task activity in providing relevant stimulus information that is perceived and utilized. Previous research conducted by the present investigator has provided evidence for the theoretical and practical significance of perceptual salience manipulations in inducing rapid discrimination learning with young developmentally delayed children of comparable chronological ages as the groups who will participate in the present series of studies.